Migrating live databases to Linux-based servers is a tricky business. Execute poorly, and your IT team will have...
figurative eggs on faces, not to mention literal downtime and data loss, says migration expert Bill Brunt. In his work on numerous migrations, Brunt -- high-availability solutions manager for Irvine, Calif.-based application management vendor Quest Software Inc. -- has seen teams get crushed when they rush. In this interview, he discusses common migration mistakes, trends in Linux adoption and SharePlex, Quest's new database replication software.
What do you see as being most common mistake that people make with Linux migrations?
Brunt: They underestimate the amount of rehearsal that's required. They know they have to practice, but they say, 'In one month, we'll do the cutover, and the cutover may take five days.' So, by the time they've planned the project and get signed off from everybody, they're only able to do it maybe once or twice.
The first time you do something, the migration team is going to run into lots of problems; so in the first round they fix those and take another crack at it and still find problems, but their time is up! Underestimating the amount of rehearsal required is the biggest mistake you can make.
What are the top two challenges an IT shop faces when migrating to Linux in the data center?
Brunt: The top two that we find are the downtime it takes and the need for a failback strategy; people want to know what happens if it doesn't work. Customers tend to choose our solutions on Linux because they really like the idea of reducing downtime or they want failback. Sometimes they do it for both, but it's interesting that they tend to favor one or the other.
Linux was first adopted as a file, print and Web platform. Where's the momentum now?
Brunt: The database is clearly happening now. A year ago, people were playing with it on Linux. We see activity now on the database side. I would say that the most conservative approach in any data center is taken with database servers. Databases are like the last domino to fall, clearly the app that shows that Linux is ready.
So, would you say that Linux is now a serious contender as a data center platform?
Brunt: Most of our Linux migrations are taking place within the data center.
Are you seeing more activity in Windows-to-Linux migrations or in the Unix-to-Linux area?
Brunt: I would say that 85% to 90% of the migration activity we've seen is from Unix to Linux. What's been driving activity there is the date that companies' maintenance contracts expire. I can think of three customers right off the top of my head who set migration dates to occur very shortly before the maintenance expired on their big Unix boxes, so they didn't have to renew.
How does Quest's new product, SharePlex, reduce the complexity of migrating databases from Unix to Linux?
Brunt: SharePlex is data replication software for Oracle on Linux. It provides support for thousands of rows per second for load distribution, disaster recovery, migrations, or for off-loading reporting. It also enables IT organizations to offload time-consuming report generation to Linux. With SharePlex, organizations can do a quick migration or introduce Linux gradually, replicating data on an ongoing basis between Linux and legacy Unix servers. One of the strengths of Quest SharePlex is that it's really light on the network. SharePlex has two phases: In one, we create the target as a copy of the original, and the other is that SharePlex keeps it in sync.
Speaking of networks, have your customers run into many networking issues during migrations?
Brunt: We are seeing a handful of customers, mostly in merger and acquisition cases, who run Solaris or HP-UX in a data center who put Linux in newer, and usually remote, data centers in a wide area network (WAN). Of course, there is more configuration required with people [who] are deciding to locate one machine outside of the corporate network or if they're dealing with a VPN. It's more complex, but we've never run into any insurmountable issue.
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